1. Field of the Invention
The present invention pertains to intravascular medical devices. More particularly, the present invention pertains to devices for capturing and removing blood clots from a blood vessel. This same system may also be used to remove material from other cavities of the body, for example, stones from the urinary or the biliary tract.
2. Background of the Art
The present invention pertains generally to thrombus collection and removal. Blood thrombus, may form a clot in a patient vasculature. Sometimes such clots are harmlessly dissolved in the blood stream. At other times, however, such clots may lodge in a blood vessel or embolize a distal blood vessel where they can partially or completely occlude the flow of blood. If the partially or completely occluded vessel feeds blood to sensitive tissue such as, the brain, lungs or heart, for example, serious tissue damage may result.
When symptoms of an occlusion are apparent, such as an occlusion resulting in a stroke, immediate action should be taken to reduce or eliminate resultant tissue damage. One approach is to treat a patient with clot dissolving drugs. These drugs, however, do not immediately dissolve the clot from the patient.
Published U.S. Patent Application 2005/0038447 describes A medical device for removing clots from a blood vessel, comprising: a first longitudinally-oriented spine having a distal end; a pushing member coupled to the proximal end of the first longitudinally-oriented spine and extending proximally therefrom; and a clot-grabbing basket generally disposed between and coupled to the first longitudinally-oriented spine.
Published U.S. Patent Application 2004/0138692 discloses an embolus extractor, comprising: an elongated shaft having a proximal end and a distal end; first and second struts, each strut having a proximal end and a distal end coupled to the distal end of the shaft; the first and second struts having a first position and a second position, wherein in the first position, the distal ends and the proximal ends of the struts are spaced at a first distance, and in the second position the distal ends and the proximal ends of the struts are spaced at a second distance, the second distance being less than the first distance; and third and fourth struts, each strut coupled to one of the first and second struts via a proximal end and distal end.
Published U.S. Patent Application 2004/0098023 discloses a vaso-occlusive device, comprising: a core member; and a fibrous structure carried by the core member, the fibrous structure comprises one or more strands of nanofibers. The vaso-occlusive device may provide the fibrous structure in a product generated at least in part by an electrospinning process comprises the steps of: supplying a polymer solution through a needle; electrostatically charging the needle; electrostatically charging a metal plate that is placed at a distance from the needle, the metal plate having a charge that is opposite that of the needle, thereby sending a jet of the polymer solution towards the metal plate; and collecting the fibrous structure from the metal plate.
Published U.S. Patent Application 2004/0039435 discloses a self-expanding, pseudo-braided device embodying a high expansion ratio and flexibility as well as comformability and improved radial force. The pseudo-braided device is particularly suited for advancement through and deployment within highly tortuous and very distal vasculature. Various forms of the pseudo-braided device are adapted for the repair of aneurysms and stenoses as well as for use in thrombectomies and embolic protection therapy.
There are a variety of ways of discharging shaped coils and linear coils into a body cavity. In addition to those patents that describe physically pushing a coil out of the catheter into the body cavity (e.g., Ritchart et al.), there are a number of other ways to release the coil at a specifically chosen time and site. U.S. Pat. No. 5,354,295 and its parent, U.S. Pat. No. 5,122,136, both to Guglielmi et al., describe an electrolytically detachable embolic device.
A variety of mechanically detachable devices are also known. Various examples of these devices are described in U.S. Pat. No. 5,234,437, to Sepetka, U.S. Pat. No. 5,250,071 to Palermo, U.S. Pat. No. 5,261,916, to Engelson, U.S. Pat. No. 5,304,195, to Twyford et al., U.S. Pat. No. 5,312,415, to Palermo, and U.S. Pat. No. 5,350,397, to Palermo et al.
Various configurations have been used to remove calculi from the biliary or urinary system. See, for instance, U.S. Pat. No. 5,064,428. Additionally, devices having various configurations have been used to remove objects from the vasculature. For example, surgical devices comprising one or more expandable and collapsible baskets have been described for removing or piercing a thrombus in the vasculature. See, U.S. Pat. No. 6,066,149. U.S. Pat. No. 5,868,754 describes a three prong-shaped device for capturing and removing bodies or articles from within a vessel.
Published U.S. Patent Application 2004/0225229 describes a device comprising a core wire having a distal end and a proximal end; a catheter shaft having a proximal catheter end, a distal catheter end and a lumen through which the core wire is passed such that the distal end of the core wire extends beyond the distal catheter end; a retrieval element disposed at the distal end of the core wire, the retrieval element movable from a radially contracted position to a radially expanded position; and a first stop element attached to the core wire, the first stop element configured to prevent over-expansion of the retrieval element.
Among commercial thrombus-removal systems are at least the following:                1) The MERCI system of Concentric Medical that has a form of a corkscrew or helix spring. In this system, which may use a large 0.018 F microcatheter, the microcatheter tip is first positioned across the thrombus with the help of a guidewire. Then the guidewire is exchanged with the system which is deployed distal and into the thrombus. The shape of the system allows it to get inserted into the thrombus. Then the thrombus is retrieved out of the artery into a large 9 French working catheter, and then out of the body.        2) The In-Time system of Boston Scientific which is a sort of a clam-shell guide, that once placed through the thrombus divides itself into 4 strings that form an oval, as with a rugby balloon. The system is pulled back to carry out the thrombus. This is similar to the disclosed structure in Published US Application 2004/0138692.        3) Another system is what is called a lasso, which is a simple catheter with a wire attached to its end. This wire makes a loop and enters back into the catheter (e.g., a large 0.018 F microcatheter). The operator changes the aspect of the loop by pulling on the wire. This system was originally conceived to catch foreign bodies.        4) The Catch system of Balt is a stent closed on one end and forming a basket that is deployed distal to the thrombus. The operator then pulls the system and retrieves the thrombus. This is similar to the structure in FIG. 7 of U.S. Pat. No. 6,805,684.The above systems may have various disadvantages, such as either to slide on the thrombus, either to fractionate, to be difficult to guide or deploy or to be traumatic to the artery while some of them are quite expensive. In addition, all these system are bulky and cannot be used in small caliber arteries.        